The disclosure concerns a device and a method for dosing toner material in an electrophotographic printer or copier. To remove toner material from a toner reservoir with a removal opening below, the removal opening is alternatively opened and closed in order to control the quantity of toner material to be removed.
In electrophotographic printers or copiers, a latent charge image is generated on a light-sensitive photoconductor material, a photoconductor drum or a photoconductor band. This charge image is subsequently inked with electrically-charged toner in a developer station of the printer or copier. The inked toner image is subsequently transferred to a carrier material, for example paper, and fixed on the material.
A one-component developer or a two-component developer is used to develop the latent charge image in the developer station. The one-component developer comprises only toner particles. The two-component developer comprises a mixture of toner particles and carrier particles. In the two-component developer, the toner particles are electrically charged via movements of the two-component developer mixture. In the one-component developer, the charging of the toner particles occurs via charge transport, for example by a carrier roller.
The toner quantity necessary to generate the toner image must be supplied to the developer station in order to be able to generate further toner images. In known printers or copiers, near the developer station a temporary storage for toner material is provided from which toner material is transported into the developer station as needed or as requested.
In known printers or copiers, the temporary storage is filled with toner material from handy toner transport reservoirs through an opening directly into the reservoir, or conveyed into the temporary storage via a transport system from a separately arranged transport reservoir. In known printers or copiers, the temporary storage near the developer station has a fill level sensor. Given a minimal fill level, toner material must be supplied to the temporary storage from the toner transport reservoir. This occurs, for example, via emptying a transport reservoir into the temporary storage. In other known arrangements, sealed reservoirs filled with toner material and in the form of bottles or cartridges are adapted to an opening in the temporary storage. The bottle or cartridge is opened by pulling a slider and/or ripping open a flap, whereby the toner material can fall into the reservoir.
However, in these solutions to refill toner material into the temporary storage, a high danger of contamination exists for operating personnel and the environment of the temporary storage upon filling of the toner material and upon removal of the emptied transport reservoir. A low weight and a small structural size of the bottles and/or cartridges in fact enables a simple manipulation and a safe handling upon refilling of the temporary storage. However, given a high toner usage a frequent refilling of the reservoir is necessary, whereby long machine downtimes are created and the operating personnel are severely stressed.
A toner reservoir and a device for contamination-free exchange of such a toner reservoir in a toner transport device of a printer or copier is known from the documents U.S. Pat. Nos. 4,990,964 and 5,074,342. Toner material is transported as needed from a toner reservoir arranged separate from the developer station into the temporary storage as needed via a tube, with the aid of suction air. A vertically displaceable suction spout is immersed through an opening arranged in the top of the toner reservoir and sucks toner material out. A special formation of the toner reservoir and a laterally connected vibrating unit provide for a nearly complete emptying of the reservoir. The suction spout is drawn from the reservoir to exchange the reservoir. The opening in the toner reservoir is always arranged on top, whereby a spillage of toner is prevented. However, the conveying capacity is strongly dependent on the fill state in the toner reservoir. The conveying capacity also decreases with a reduction of the fill level, such that the printing event is interrupted given a low toner level in the reservoir and a simultaneously large toner requirement in the developer station. The vibrating unit also causes disturbing noises.
An apparatus to convey toner material from a reservoir by means of a suction and pressure unit that protrudes into the reservoir is also known from the document U.S. Pat. No. 5,915,154. Toner material is interspersed with gas with the aid of the suction and pressure unit, such that the toner material to be vacuumed is mixed into a powder-gas mixture, whereby the suction of the fine-powder toner material from the reservoir is eased. However, the problem also occurs in this known device that the conveying capacity also decreases with a decrease of the fill level in the reservoir, leading to an already-described interruption of the print process as a consequence of a too-small toner material redelivery.
From the documents EP-A-0 412 923 and U.S. Pat. No. 4,277,003, devices are known that contain a conveying element rotating horizontally that seal the lower opening of the toner reservoir.
Paddlewheels to convey powdered materials are known from the documents U.S. Pat. Nos. 2,643,032 and 3,231,105.
A method is known from the document U.S. Pat. No. B-6,229,975 in which a toner-air mixture is siphoned off through a filter, whereby the toner material deposits in the filter.
From the documents Patent Abstracts of Japan Vol. 2000, Nr. 01, 31 Jan. 2000 (2000-Jan.-31), JP 11282238 and U.S. Pat. No. 5,915,154, methods are known in which a toner-air mixture is conveyed from a temporary storage into a plurality of conveyed further via rotation of the paddlewheel. The quantity of the conveyed toner material can be simply controlled via the rotary speed or via angular momentums of the paddlewheel, whereby the toner material quantity can be does in simple fashion. The conveyed quantity of toner material is thus dependent on the rotary developer stations. From the document U.S. Pat. No. 5,915,154 it is also known to provide what are known as air separators to separate air and toner.
From the document U.S. Pat. No. 5,201,349, a device is known for decanting toner from a transport container into a reservoir. A cleaning device for the mechanical removal of toner material from a filter insert that serves to separate toner and air is also known.
From the document U.S. Pat. No. 5,727,607, a method and a device to convey toner material are known in which a gaseous medium is supplied to the toner material.
From the document EP-A-0 494 454, it is also known to fluidize a powdered toner material with the aid of air. This can be excited to vibration to empty the toner reservoir.
From the document Patent Abstracts of Japan, Vol. 015, Nr. 480 (P-1284), 5 Dec. 1991 (1991-12-05)-JP03208066A, a toner supply reservoir is known with side walls running downwards at an incline to one another.